Method and apparatus for object recognition and warning system of a primary vehicle for nearby vehicles

ABSTRACT

A vehicle to vehicle warning system comprises a transmitter associated with a primary vehicle alerting one or more secondary vehicles of its proximity through a receiver. The transmitter may emit a radio frequency signal which activates radio frequency receivers in surrounding vehicles. When in appropriate proximity, the signal is configured to initiate a warning at the secondary vehicle, such as light from a light-emitting device or sound from a sound-generating device. In another form, the primary vehicle includes a passive transmitter and the secondary vehicle includes a multi-frequency resonance tag/circuit having distinct frequencies for detection and discrimination. The passive transmitter creates electromagnetic waves which are generated as it passes by the secondary vehicle housing the multi-frequency resonance tag, setting off the secondary vehicle alarm system.

RELATED APPLICATION DATA

This application is a divisional of U.S. patent application Ser. No.12/229,304, filed on Aug. 20, 2008, which is a continuation-in-part ofU.S. patent application Ser. No. 11/820,847, filed Jun. 20, 2007, whichclaims priority to U.S. Provisional Patent Application Ser. No.60/815,353, filed Jun. 21, 2006, and also claims priority to U.S.Provisional Patent Application Ser. No. 60/966,112, filed Aug. 24, 2007,and U.S. Provisional Patent Application Ser. No. 60/995,173, filed Sep.24, 2007.

FIELD OF THE INVENTION

The present invention relates to a method and apparatus for providing avehicle to vehicle warning system. More specifically, the invention is amethod and apparatus by which a primary vehicle, such as an ambulance,fire truck, police car, school bus, or train, warns of its proximity toone or more secondary vehicles.

BACKGROUND OF THE INVENTION

In order to provide a warning to others, vehicles such as ambulances,fire trucks and police cars (“primary vehicles”) may utilize loud sirensor flashing lights. Those warnings are generally provided for drivers ofother vehicles (“secondary vehicles”). Unfortunately, these warningmethods are often not effective, not being heard or seen by drivers orpassengers of the secondary vehicles. Other warning means may providewarnings via the secondary vehicle radio. However, communicationssystems that utilize a secondary vehicle's radio are also notparticularly effective, since the driver of the vehicle may not havetheir radio turned on.

Various prior art exists which describes signal generators and use ofthose signals. However, this prior art does not teach or suggest awarning signal system which is effective for use with vehicles.

U.S. Pat. No. 5,661,470 (Karr) This invention relates to LC respondersand particularly to LC responders that are placed within objects such astoys. In operation, an interrogation or base unit sends a pulse andpassive responders reply with their unique frequency which is sensed bythe base unit triggering a particular response such as turning on amotor etc.

U.S. Pat. No. 4,023,167 (Wahlstrom) teaches a system in which bursts ofradio frequency are transmitted to excite and thereby detect thepresence of passive resonant circuits. If a circuit is resonant at aparticular burst frequency, it is excited, rings and emits a radiofrequency signal. Following each transmitted burst, a receiver is turnedon to receive energy emitted by the resonant circuit so that if aresonant circuit is excited, its emitted energy is received and theparticular resonant circuit can be identified.

U.S. Pat. No. 3,863,244 (Lichtblau) is an electronic security systemadapted having improved noise discrimination for use in a controlledarea such as a retail store and employing a multi-frequency resonancetag circuit having distinct frequencies for detection anddiscrimination.

U.S. Pat. No. 3,895,368 (Gordon) describes an apparatus in which amicrowave signal generator projects an electromagnetic wave into a spaceunder surveillance to establish a first field. A pulse or frequencymodulated low frequency generator is used to apply a voltage to adiscontinuous conductor for establishing a second field, electrostaticin nature, throughout the space. Presence in the space of a miniature,passive, electromagnetic wave receptor-reradiator in the form of asemi-conductive diode connected to a dipole antenna causes thereradiation of the low frequency component modulated on the microwavecomponent as a carrier. The front end of a receiver system is tuned tothe microwave frequency signal. A coincidence circuit energizes an alarmcircuit whenever the detected signal coincides with the originalmodulation envelope being applied to the low frequency generator.

SUMMARY OF THE INVENTION

The present invention is an inexpensive, simple, and independent warningsystem for a primary vehicle to alert its proximity to a plurality ofsecondary vehicles. These secondary vehicles will then be able to yieldin a timely fashion to the primary vehicle.

In one embodiment, a primary vehicle is equipped with a transmitter andthe secondary vehicles are equipped with receivers, and the secondaryvehicles are configured to provide or initiate a warning in the event asignal is detected from a primary vehicle. The transmitter and/or signalmay be active, such as a transmitter transmitting a wireless signal, orpassive, such as a transmitter/signal which is detectable by thesecondary vehicle.

One aspect of the invention is a method and apparatus that comprises aradio transmitter in the primary vehicle and radio receivers in thesecondary vehicles.

Another form of the invention relates to a method and apparatus thatcomprises the primary vehicle housing a multi-frequency a microwavesignal generator which transmits an electromagnetic wave into secondaryvehicles which house a receiver system tuned to the microwave frequencysignal. A coincidence circuit energizes an alarm circuit whenever thedetected signal coincides with the original modulation envelope beingapplied to the low frequency generator.

In yet another embodiment, the transmitter associated with the primaryvehicle is passive and configured to be detected by receiver or detectorassociated with the secondary vehicle(s). Such a system may employ radiofrequency identification devices (RFIDs).

The warning system preferably includes a warning device in the secondaryvehicle. The warning system may comprise an existing audio system of thevehicle, where the system is configured to generate an audible and/orvisible warning.

Further objects, features, and advantages of the present invention overthe prior art will become apparent from the detailed description of thedrawings which follows, when considered with the attached figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates an active vehicle to vehicle warning system inaccordance with one embodiment of the invention, wherein a primaryvehicle includes a transmitter configured to generate and transmit awarning signal for detection by one or more secondary vehicles;

FIG. 2 illustrates a passive vehicle to vehicle warning system inaccordance with one embodiment of the invention, wherein a primaryvehicle which includes a passive transmitter which is detected by adetector of a secondary vehicle; and

FIG. 3 schematically illustrates secondary vehicle warning system of theinvention wherein a receiver is associated with an existing audio systemof the secondary vehicle.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, numerous specific details are set forth inorder to provide a more thorough description of the present invention.It will be apparent, however, to one skilled in the art, that thepresent invention may be practiced without these specific details. Inother instances, well-known features have not been described in detailso as not to obscure the invention.

In general, the invention is a system and method for providing warningsto vehicles. In one embodiment, a primary vehicle includes atransmitter. The transmitter may be passive, such as to be detected by asecondary vehicle. The transmitter may alternatively be active, such asto transmit a wireless signal. Preferably, the system and method allow asecondary vehicle to be provided a warning regarding the presence of aprimary vehicle. The invention may also be utilized to provide warningsto secondary vehicles from areas or objects other than primary vehicles.For example, secondary vehicles may be provided with a warning regardinga construction zone or area.

Primary Vehicle with Active Transmitter

In one embodiment, a primary vehicle is configured to transmit awireless signal to a secondary vehicle. The primary vehicle ispreferably equipped with or otherwise includes a signalgenerator/transmitter. The wireless signal may be of a variety of types,including digital or analog and be at various frequencies.

In one embodiment, a primary vehicle includes a radio transmitter. Theradio transmitter can emit signals on a variable basis with respect todistance and frequency. The signal can be independent or dependent onthe primary vehicle's speed or distance. The device which emits thesignal can be manually or automatically activated.

The frequency of the signal may be, for instance, a Very Low Frequency(VLF). The signal is transmitted from the primary vehicle for receipt byone or more secondary vehicles. In one embodiment, the secondary vehicleincludes an appropriate receiver for receiving/detecting the transmittedsignal. Preferably, the received signal is utilized to create a warningevent.

In one embodiment, a detected VLF signal is modulated to a visual andauditory early warning signal in the secondary vehicle. The VLF signalmay be modulated or otherwise utilized to alter the existingelectronics, such as the radio, of the secondary vehicle. The Very LowFrequency signal may act as a form of Electromagnetic Interference orEMI.

Electromagnetic Interference or EMI, has been defined as the“degradation of the performance of a piece of equipment, transmissionchannel, or system caused by an electromagnetic disturbance.” (ANSIC63.14, 1992; IEC 60050(161), 1990). EMI can occur throughout the EMspectrum from 0 Hz to 20 GHz or higher frequencies. However, EMIproblems are most prevalent in the RF frequencies. For anElectromagnetic Interference or EMI condition to exist, the followingconditions must be present:

(1) There must be a source. An interference source is called an“emitter” of electromagnetic energy. The emitter may propagateelectromagnetic energy either intentionally, like a hand held radio, orunintentionally, like a power transformer.

(2) There must be a device sometimes referred to as the “victim”, thatis susceptible to the electromagnetic energy being emitted by theemitter source. If the susceptible device does not have sufficientimmunity to reject the energy it is being exposed to, electromagneticinterference may occur.

(3) A physical relationship must exist between the two devices whereinthey share a common propagated electromagnetic field. The physicaldistance between devices and their spatial orientation with respect toeach other may have a significant role in determining whether thedevices will react with each other.

The sensitivity of a device to EMI is described by either susceptibilityor immunity. Since susceptibility to EMI varies with many factors,devices can be placed into an active electromagnetic field without userawareness that a potential EMI problem may exist. Adjacent devices mayalso unintentionally radiate electromagnetic fields that can, in turn,affect other devices.

The frequency, for instance, can be a Radio Frequency InterferenceSignal. The signal may be transmitted to the receiver in the secondaryvehicle. The VLF signal is then modulated to a visual and auditory earlywarning signal in the secondary vehicle. The VLF signal is thenmodulated to alter the existing electronics, including the radio, of thesecondary vehicle.

Radio frequency interference (RFI) is electromagnetic radiation which isemitted by electrical circuits carrying rapidly changing signals, as aby-product of their normal operation, and which causes unwanted signals(interference or noise) to be induced in other circuits. Thisinterrupts, obstructs, or otherwise degrades or limits the effectiveperformance of those other circuits. It can be induced intentionally, asin some forms of electronic warfare, or unintentionally, as a result ofspurious emissions and responses, intermodulation products, and thelike. It is also known as electromagnetic interference or EMI. RFIfrequently affects the reception of AM radio in urban areas. It can alsoaffect FM radio and television reception, although to a lesser extent.

The most important means of reducing RFI are: use of bypass or“decoupling” capacitors on each active device (connected across thepower supply, as close to the device as possible), risetime control ofhigh speed signals using series resistors and VCC filtering. Shieldingis usually a last resort after other techniques have failed because ofthe added expense of RF gaskets and the like.

The efficiency of the radiation is dependent on the height above theground or power plane (at RF one is as good as the other) and the lengthof the conductor in relationship to the wavelength of the signalcomponent (fundamental, harmonic or transient (overshoot, undershoot orringing)). At lower frequencies, such as 133 MHz, radiation is almostexclusively via I/O cables; RF noise gets onto the power planes and iscoupled to the line drivers via the VCC and ground pins. The RF is thencoupled to the cable through the line driver as common node noise. Sincethe noise is common mode, shielding has very little effect, even withdifferential pairs. The RF energy is capacitively coupled from thesignal pair to the shield and the shield itself does the radiating. Onecure for this is to use a braid-breaker to reduce the common modesignal.

At higher frequencies, usually above 500 MHz, traces get electricallylonger and higher above the plane. Two techniques are used at thesefrequencies: wave shaping with series resistors and embedding the tracesbetween the two planes.

Referring to FIG. 1, the one or more secondary vehicles SV include adetector configured to detect the signal emitted by the transmitter ofthe primary vehicle PV. The detector may comprise a receiver, such as aradio frequency receiver configured to receive radio frequency signals.

In one embodiment, the transmitter is associated with the primaryvehicle, such as being housed within or otherwise mounted to the primaryvehicle. The transmitter may be powered by one or more power sources,such as an electrical system of the vehicle, a battery or the like.Similarly, the detector is associated with the secondary vehicle, suchas being housed within or otherwise mounted to the secondary vehicle. Aswith the transmitter of the primary vehicle, the detector may be poweredby various power sources, such as the electrical system of the secondaryvehicle or a battery.

As detailed below, the system preferably includes one or more warningdevices for the secondary vehicle. The warning devices may be integralwith the detector of the secondary vehicle, or comprise other elements,such as an existing audio and/or video system of the secondary vehicle.In one embodiment, in the event the detector detects a signal from thetransmitter, a warning is provided at the secondary vehicle. This maycomprise the detector generating a signal which is output to the warningdevice, such as a signal which causes an audible or visible warning tobe displayed at the secondary vehicle.

Primary Vehicle with Passive Transmitter

In another embodiment, as illustrated in FIG. 2, the primary vehicle PVmay be provided with a passive transmitter. In such a configuration, thesecondary vehicle SV may be configured to detect the presence of thepassive transmitter, such as by itself transmitting a signal.

In one embodiment, the primary vehicle may be configured with anelectronic tag, while the secondary vehicle may be configured with atransmitter or receiver configured to detect the presence, in acontrolled space or area, of that tag (and thus primary vehicle). Forexample, the system may include a radio frequency identifier, or otherpassively detectable element such as a miniature, passive electricsignal receptor-reradiator configured to provide a warning of thepresence of a primary vehicle to a secondary vehicle.

The tag, such as radio frequency identifier, may be configured to bedetected by a detector associated with the secondary vehicle.

In accordance with one aspect of the present invention there is provideda method of detecting, within a confined space, an electric signalreceptor-reradiator which has signal-mixing capability. The method maycomprise the steps of simultaneously establishing in the controlledspace first and second energy fields. The first energy field is chosento be electromagnetic in nature and is produced by a continuousmicrowave signal for causing the receptor-reradiator to return a signalthere from. The second field is chosen to be electrostatic in natureestablished by applying signal voltage to a discontinuous conductorrelative to a point of reference potential and having a sufficiently lowfrequency to enable it to be confined substantially to the controlledspace. Detection in the space of a signal consisting of a carrier andmodulation components where the components are due respectively to saidfirst and second fields is indicative of the presence of thereceptor-reradiator therein.

In accordance with another aspect of the present invention, there isprovided a vehicle to vehicle warning system for detecting the presencein a controlled space of a receptor-reradiator, said system comprisingin combination a source of continuous microwave signals, means coupledto the source of microwave signals for propagating through said space anelectromagnetic wave corresponding to the microwave signals, a source oflow frequency signals, a discontinuous conductor coupled to the sourceof low frequency signals for establishing through the space anelectrostatic field corresponding to the low frequency signals, signaldetecting means, means for coupling the detecting means with the spacefor receiving signals there from the detecting means being constructedand arranged to detect the low frequency signals only when received asmodulation on a carrier signal whose frequency bears a predeterminedrelationship to that of the microwave signals, and means coupled to thedetecting means for providing an alarm responsive to the detection ofthe low frequency signals.

Once again, in this embodiment, the passive transmitter is preferablyassociated with the primary vehicle, such as by being mounted to orassociated with the primary vehicle. The detector of the secondaryvehicle is similarly associated. Further, this embodiment systempreferably also again includes at least one warning device for providinga warning at the secondary vehicle.

EXAMPLES

As one example of the invention, a passenger vehicle may have an activetransmitter associated therewith, i.e. the vehicle transmits a signalwithout being externally prompted, such as by transmitting a signalwithout prompting by an external trigger signal (as indicated below, forexample, such an active transmitter may be configured by a manufacturerof the vehicle to always transmit a signal). This transmitter may send afirst signal which may be received by a receiver of a primary vehicle(such as an emergency vehicle). In one embodiment, the activetransmitter may send a variety of signals and/or information. Thisinformation may, but need not be, encoded (such as encrypted). Forexample, each secondary vehicle, such as passenger vehicle, may transmita vehicle identification number (VIN), vehicle registrationnumber/license plate, randomly generated number or the like. The primaryvehicle receiver is configured to receive (if the signal is in range)and, if necessary, decode that signal.

The primary vehicle may also be configured with a transmitter which isconfigured to respond to the receipt of the signal from the secondaryvehicle with a responsive or second signal, as illustrated in FIG. 2.Such a responsive signal is transmitted from the primary vehicle back tothe secondary vehicle (with or without encoding/encryption) forreception at the secondary vehicle. Once again, this return signal maybe a variety of signals and/or information. For example, the informationmay be encoded, and may be configured to be received only by theoriginal source (i.e. the vehicle having the VIN or other identifierwhich transmitted the original active signal). For example, thesecondary vehicle receiver may be configured to decode only signalsreceived from a primary vehicle which match the vehicle's VIN or otheridentifier.

In one embodiment, this concept may be applied to other types ofenvironments. For example, a passive receiver/transmitter may be locatedat a primary location other than a vehicle, such as store or the like.In such a configuration, a vehicle traveling in the area sends out anactive signal which is received at the secondary location, such as astore. In response, the transmitter at the store may be configured totransmit a responsive or second signal back to the vehicle. This signalmight be an advertisement or the like. For example, vehicle traveling onthe freeway might send a signal which is detected by a local gasstation, and the gas station may send a signal back that causesinformation to be provided at the vehicle (such as via a display, GPS oraudio system at the vehicle) of the location of the gas station, gasprices or the like. In such a configuration, the system may primarilyact as a system for providing information to a vehicle in proximity to aparticular location.

Of course, a wide variety of information might be transmitted back tothe secondary vehicle upon receipt of the signal therefrom. Thisinformation might comprise a warning of an emergency vehicle, otherwarnings such as weather warning or road closures, commercialadvertising and the like.

In one embodiment, the signal which is transmitted back to the secondaryvehicle from the passive receiver/transmitter might be utilized by thesecondary vehicle to provide other than warnings. For example, uponreceipt of the signal from a secondary vehicle, a police officer in anearby car might cause a signal to be transmitted back to the vehiclewhich causes the vehicle engine to be shut off (such as in the case of afleeing suspect). In this regard, the receiver at the secondary vehiclemay be integrated into or otherwise control various aspects of thevehicle's control system.

In one embodiment, one or more safeguard or security features may beemployed to ensure that the system is operable relative to a particularsecondary vehicle. For example, the secondary vehicle may be equippedwith a relay, sensor or other means for detecting the operation of thetransmitter/receiver associated therewith. If the transmitter/receiveris detected as not being operable or not operating correctly, a warningmay be provided to the operator of the secondary vehicle or thesecondary vehicle may be disabled. A warning might comprise a visual oraudio alert. Disablement of the vehicle might be accomplished through anignition circuit, computer engine control or the like. Similarly, meansmay also be provided for ensuring that signals are being transmitted andreceived properly, and for providing an alert or disabling the vehicleif such a condition is not confirmed. For example, thetransmitter/receiver may be configured to send a test or link signal (atstart up or periodically) to the passive receiver/transmitter of theprimary vehicle (or even network response devices positioned in variouslocations), which sends a response. If a response it not confirmed, suchas in the case signals are being jammed, the transmitter/receiver of thesecondary vehicle may again be configured to provide an alarm or disablethe secondary vehicle. Such features may be utilized to prevent avehicle owner from disabling their transmitter/receiver or jamming thesignal transmitted from their vehicle to prevent its operation.

In one embodiment, the active transmitter at the secondary vehicle mayalways be active (such as configured by the manufacturer to alwaystransmit or transmit when the vehicle is running). In other embodiments,the operator might turn the system, or features thereof, on or off. Forexample, the operator of the secondary vehicle might not wish to obtainadvertising from local businesses as they drive by, so they might turnoff the transmitter or at least that feature. As detailed below, thesefeatures may be configured via software and/or hardware, and appropriateuser interfaces and inputs (such as user input buttons or touchscreens), may be provided for implementing the features.

Various aspects of the invention will now be appreciated.

One aspect of the invention is a vehicle equipped with a signalproducing transmitter, such as a radio-frequency transmitter employingone or more oscillators to generate a radio-frequency signal. Theinvention may also comprise a device housed in a primary vehicle tomodulate imprinting data, intelligence, onto an electric current orelectromagnetic wave by varying amplitude, frequency, or phase of thewave (carrier) to effect emission. The transmitter may also beconfigured to transmit a digital signal, including such a signal encodedwith information.

In one embodiment, a secondary vehicle includes at least one device,such as a receiver. In one embodiment, the receiver may simply beconfigured to detect the presence of a signal emitted by the transmitterof the primary vehicle, or receive and/or convert such a signal, such asby converting EM waves into the original signals sent from a distanttransmitter. The device may comprise a crystal set acting as ademodulator to recover the modulating waveform from the signal, adirect-conversion receiver which mixes incoming signals with the outputof a variable-frequency local oscillator, or a superheterodyne receiverto obtain an output signal that is always at the same frequency, orwithin a fixed, narrow range of frequencies.

The secondary vehicle receiver or other device may be configured tomodify sensitivity to produce a certain signal-to-noise ratio (S/N) orsignal-plus-noise-to-noise ratio (S+N/N), to modify selectivity todetermine the receivers passband, or range of signal frequencies that isallowed through the system at any given time, to control the receiversdynamic range, a measure of the extent to which a receiver can maintaina fairly constant output, as well as, keep or eliminate signals fromweak to strong, and/or to control noise figure, a measure of the amountof noise a radio generates inside its own circuits.

The device may also comprise an RF amplifier, or front end, thatincludes selective filters between an amplifier and an antenna, whichdetermine the dynamic range and sensitivity of the receiver, whichconverts the variable signal frequency to a constant IF, or provide IFstages, where selectivity can be obtained utilizing filters, includingdigital signal processing, to achieve the desired bandwidths andresponses.

The device may include a detector which extracts information orintelligence from the signal. The signal may be amplified suitable tolistening with a speaker or viewing by a display.

The device may include a processor, computer readable code (software)and other appropriate hardware, such as data storage or memory devices(such as RAM). A shift register may be implemented in software in themicroprocessor, said microprocessor software reads in each bit, shiftssaid bits to bytes, and stores the bytes in RAM.

As indicated above, the method and system of the invention may beimplemented in a variety of configurations.

In one embodiment, the invention is a method and apparatus for a vehicleto vehicle warning system within a confined area to detect the presencein the area or space of an electric signal receptor-reradiator withsignal mixing capability, the method comprising the steps ofsimultaneously establishing in the space first and second energy fields,the first field being electromagnetic in nature and produced by acontinuous microwave signal for causing the receptor-reradiator toreturn a signal there from, the second field being electrostatic innature established by applying a signal voltage to a discontinuousconductor relative to a point of reference potential and having asufficiently low frequency to enable it to be confined substantially tosaid space, and detecting the presence in the space of a signalconsisting of a carrier and modulation components where the componentsare due respectively to the first and second fields and where the secondfield may be produced with a frequency modulated signal.

Another embodiment of the invention is a method and apparatus for avehicle to vehicle warning system within a confined area for detectingthe presence of a miniature passive electromagnetic wavereceptor-reradiator with signal mixing capability, the system comprisingin combination, a source of continuous microwave signals, means coupledto a source of microwave signals for propagating through space anelectromagnetic wave corresponding to the microwave signals, a source oflow frequency signals, a discontinuous conductor coupled to aid inestablishing low frequency signals for establishing through said spacean electrostatic field corresponding to said low frequency signals, thelow frequency signals having a sufficiently low frequency to enable theelectrostatic field to be confined substantially to the area or space,signal detecting means, means for coupling the detecting means with thespace for receiving signals there from, the detecting means beingconstructed and arranged to detect said low frequency signals only whenreceived as modulation on a carrier signal whose frequency bears apredetermined relationship to that of the microwave signals, and meanscoupled to the detecting means for providing an alarm responsive todetection of the low frequency signals, and where the discontinuousconductor may comprise a plate-like member.

Yet another embodiment of the invention is a method and apparatus for avehicle to vehicle warning system within a confined area for detectingthe presence in a controlled space of a miniature passive diode-dipoleelectromagnetic wave receptor-reradiator with signal mixing capability,the system comprising, in combination, a source of microwave signals,means coupled to the source of microwave signals for propagating throughthe space an electromagnetic wave corresponding to the microwavesignals, a source of low frequency signals, a discontinuous conductorcoupled to the source of low frequency signals for establishing throughthe space an electrostatic field corresponding to the low frequencysignals, the low frequency signals having a sufficiently low frequencyto enable the electrostatic field to be confined substantially to thespace, signal detecting means, means for coupling the detecting meanswith the space for receiving signals there from, the detecting meansbeing constructed and arranged to detect the low frequency signals onlywhen received as modulation on a carrier signal having the samefrequency as the microwave signals, and means coupled to the detectingmeans for providing an alarm responsive to detection of the lowfrequency signals. The means may be coupled to the source of lowfrequency signals for pulse modulating the latter, where the means forproviding an alarm are coupled to the pulse modulating means forproviding the alarm only when the detected low frequency signal has awave envelope coinciding with an output of the pulse modulating means.

In one embodiment, the invention is a method and apparatus for a vehicleto vehicle warning system within a confined area detecting the presencein a controlled space of a miniature passive electromagnetic wavereceptor-reradiator with signal mixing capability, the system comprisingin combination a source of microwave signals, means coupled to thesource of microwave signals for propagating through the space anelectromagnetic wave corresponding to the microwave signals, a source oflow frequency signals, means coupled to the source of low frequencysignals for frequency modulating the latter with a modulating signal,further means coupled to the source of low frequency signals forestablishing through the space an electrostatic field corresponding tothe low frequency signals, the low frequency signals having asufficiently low frequency to enable the electrostatic field to beconfined substantially to the space, signal detecting means, means forcoupling the detecting means with the space for receiving signals therefrom, the detecting means being constructed and arranged to detect thelow frequency signals only when received as modulation on a carriersignal whose frequency bears a predetermined relationship to that of themicrowave signals, and means coupled to the detecting means forproviding an alarm responsive to detection of the low frequency signals.The means for providing an alarm may be coupled to the frequencymodulating means for providing the alarm only when the detected lowfrequency signals are frequency modulated with a wave envelope havingthe same shape as the modulating signal, where the frequency modulationof the source of low frequency signals may be characterized by afrequency deviation of the order of 1 KHz.

In another embodiment, the invention is a method and apparatus for avehicle to vehicle warning system within a confined area for detectingthe presence in a controlled space of a miniature passiveelectromagnetic wave receptor-reradiator with signal mixing capability;the system comprising in combination a source of microwave signals;means coupled to the source of microwave signals for propagating throughthe space an electromagnetic wave corresponding to the microwavesignals; a source of low frequency signals; means coupled to the sourceof low frequency signals for establishing through the space anelectrostatic field corresponding to the low frequency signals; the lowfrequency signals having a sufficiently low frequency to enable theelectrostatic field to be confined substantially to the space; thesource of low frequency signals comprising a voltage-controlledmulti-vibrator pulse generator, means coupled to an output of the pulsegenerator for converting a square wave signal to a sinusoidal signal foruse in establishing the electrostatic field, and means coupled to thepulse generator for frequency modulating the latter with a modulatingsignal; signal detecting means; means for coupling the detecting meanswith the space for receiving signals there from, the detecting meansbeing constructed and arranged to detect the low frequency signals onlywhen received as modulation on a carrier signal whose frequency bears apredetermined relationship to that of the microwave signals; and meanscoupled to the detecting means for providing an alarm responsive todetection of the low frequency signals.

As indicated above, the components of the system may be powered by anelectrical system of the vehicles with which they are associated. In oneor more embodiments, the system and/or device of the invention mayinclude a battery operated power supply.

In one embodiment, when the secondary vehicles receive a signal from aprimary vehicle or otherwise detects the primary vehicle, a warning isprovided. The warning may comprise, for example, the illumination of alight or lights or generation of sounds at the secondary vehicle, so asto provide a warning to the driver and/or passengers. The lights whichare illuminated may be one or more of those already normally associatedwith the vehicle, or the light or light may be special warning lights(such as a special dash-board light). Sounds may be generated using anexisting audio system, or by special devices, such as a buzzer or thelike.

FIG. 3 illustrates an embodiment of the invention in which a secondaryvehicle includes a receiver R for detecting a primary vehicle. Thereceiver R also includes an integrated warning signal generator. Thereceiver R is powered by the power supply P of the vehicle, whichincludes a ground G. The generated warning signal is provided to acontroller C, such as an audio control unit of the vehicle. This signalcauses the controller C to output a signal to one or more speakers S ofthe vehicle, thus providing an audible warning.

It will be appreciated that this configuration is but one example of awarning device for a secondary vehicle. For example, the system couldinclude one or more dedicated audio and/or video devices.

As one implementation of the system and method, primary vehicle may beequipped with a wireless signal generator and transmitter. A secondaryvehicle may be equipped with a receiver for receiving the transmittedwireless signal. In response to receipt of the signal, the receiver maybe configured to generate and output a warning activation signal ordirectly generate a warning. For example, the transmitted signal may bereceived and activate a relay which causes the existing hazard lights ofthe secondary vehicle to activate (providing both the driver and partiesexterior to the secondary vehicle with notice of the warning). Ofcourse, the transmitted signal might be used to initiate a variety ofother warnings at the secondary vehicle, whether via existing vehiclecircuitry or via other devices.

It will be understood that the above described arrangements of apparatusand the method there from are merely illustrative of applications of theprinciples of this invention and many other embodiments andmodifications may be made without departing from the spirit and scope ofthe invention as defined in the claims.

What is claimed is:
 1. A vehicle information system comprising: atransmitter associated with a first vehicle, said transmitter configuredto actively transmit a first signal; a receiver associated with amerchant location, said receiver configured to receive said first signalwhen said first vehicle is within range of said second location; atransmitter associated with said merchant location, said transmitterconfigured to transmit a second signal to said first vehicle uponreceipt of said first signal; and a receiver associated with said firstvehicle, said receiver configured to receive said second signal andprovide information at said first vehicle, said information comprisingadvertising regarding goods or services offered by said merchant.
 2. Thesystem in accordance with claim 1 wherein said merchant location is abuilding.
 3. The system in accordance with claim 1 wherein said merchantlocation comprises a store.
 4. The system in accordance with claim 1wherein said information comprises pricing of goods or services of saidmerchant.
 5. The system in accordance with claim 1 wherein saidinformation is presented via the controller of the first vehicle intothe audio or video system at said first vehicle.
 6. The system inaccordance with claim 1 wherein said first signal includes vehicleidentification information.
 7. The system in accordance with claim 1wherein said first signal is encoded.
 8. The system in accordance withclaim 1 wherein said second signal is encoded for use solely by saidreceiver of said first vehicle.
 9. The system in accordance with claim 1further comprising means for detecting an operating condition of saidtransmitter and receiver of said first vehicle, said means configured totrigger an alarm or deactivation signal to said first vehicle if aninoperable condition is detected.